This invention relates to floor sweepers, particularly carpet sweepers, which in addition to the usual brush roller, are provided with auxiliary rotary brushes at the front of the sweeper frame for sweeping debris into the path of the brush roller.
Broadly, such auxiliary brushes are already known, as in the above referred to patents. For example, in the very early days of carpet sweepers, it was already suggested to mount an auxiliary brush having an annular array of bristles on a fixed axis which was inclined slightly from the vertical. See the U.S. Pat. 500,976. In the sweeper of that patent, the auxiliary brush drive connects from the top of the auxiliary brush body ad through a suitable shaft to a special drive wheel located centrally beneath the housing. Such a sweeper is expensive to manufacture and repair.
It is also known to rotatably drive the auxiliary brush body from an external drive wheel and wherein the brush is mounted to tilt fore and aft on a horizontal axis in accordance with the direction of sweeper movement. See the U.S. Pat. 3,750,215. This type of structure is also complex and expensive.
Other known auxiliary brush devices have attempted to simplify the drive structure by eliminating the external drive and instead providing a rotary drive for the auxiliary brush which is disposed within the confines of the annular bristles and which engages the floor beneath the brush body. Thus, it is known to drive the brush by means of an angular gear wheel disposed within the brush and which engages the floor. See the German Pat. No. 2,055,841. In that sweeper, the entire brush assembly swivels about a vertical axis during fore and aft sweeper movement. The resulting structure is heavy and relatively costly to produce.
It is also known to drive the brush from a spring loaded wheel beneath the brush body and to also tilt the entire brush assembly about a horizontal axis. See the U.S. Pat. No. 3,874,016. This structure is also complex and expensive to manufacture.
Several drives which have been further simplified are also presently known. For example, in German Petty Pat. No. 7324485, an auxiliary brush is mounted on a fixed vertical axis and the body thereof is provided with the usual annular array of sweeping bristles. A second array of inclined bristles is disposed inwardly of the sweeping bristles and is intended to drive the latter by contact with the floor. This construction is subject to several disadvantages. Not only do the second set of bristles substantially increase the cost of the assembly, but also it has been found that this brush tends to stall on the carpet during normal sweeper use, thus making the brush substantially unusable.
Another example of simplified auxiliary brush is shown in U.S. Pat. No. 3,748,679, wherein the brush body freely floats along the inclined shaft of a caster wheel and with the latter driving the brush through a non-circular connection. It has been found that this known structure, while performing relatively well under normal circumstances, does have at least one disadvantage. When the sweeper is moved along a wall in an attempt to remove debris at the floor-wall edge, the brush tends to stall when it contacts the wall.
To the knowledge of the inventor, the auxiliary brushes of the known devices have, upon forward sweeper movement, turned so that their forward edges rotated transversely inwardly and then rearwardly to beneath the sweeper housing. That is, viewed from the top, the right front corner brush has rotated counterclockwise and the left front corner brush clockwise. This has previously been thought to be desirable to obtain sweeping of the debris along a wall inwardly into the path of the brush roller.